Why do earthquakes happen, how can we explain their causes and scientific principles, and what can we do about them?

Earthquakes are natural disasters caused by plate tectonic movements in the Earth and are measured by magnitude and intensity. Understanding how earthquakes occur, the types of seismic waves, and what to do in the event of an earthquake is important to minimize damage.

 

In 2011, a powerful 9.0-magnitude earthquake in Japan sent tremendous shocks throughout the country, triggering a tsunami that caused massive loss of life and property damage. The earthquake was also linked to the Fukushima nuclear power plant disaster, which caused international repercussions. A similarly large earthquake struck Chile in 2010, with a magnitude of 9.5, making it one of the most powerful earthquakes in recorded history. As you can see, earthquakes are more than just natural disasters; they’re one of the hardest things for humanity to prepare for. So what are earthquakes, and why do they happen? To understand this, we need to learn about the Earth’s internal structure and how it works.
An earthquake is a natural phenomenon that literally means “the earth rumbles”. To be more precise, an earthquake is a sudden rupture in the rocks of the earth caused by internal forces that cause the earth to shake. This energy is transmitted as seismic waves, which travel over the ground and are felt by people. There are two main measures used to measure the strength of an earthquake: magnitude and intensity. Many people come across the words magnitude and intensity in the news or when reading about earthquakes, but it’s easy to confuse the two concepts.
Magnitude is a measure of the absolute intensity of an earthquake. It’s usually measured on the Richter scale or the moment scale. Most of the earthquake magnitudes we hear about in the news are based on magnitude. Intensity, on the other hand, is the relative strength of the earthquake as it is actually felt in a particular place. The closer you are to the epicenter of an earthquake, the stronger it is felt, and the farther away it is felt, the weaker it is. It’s similar to how a stone thrown into water causes waves to spread out.
Why do earthquakes happen? To answer this question, we need to understand the Earth’s plate tectonics. The ground we stand on is not static, but the huge plates that make up the Earth’s surface are constantly moving. These plates float on top of the upper mantle and move very slowly but steadily as the mantle moves. When the plates bump or push against each other, they create an impact, which is what causes an earthquake. Because plate movement happens so slowly, people don’t feel it, but when this movement builds up over a long period of time and is suddenly released, it creates a powerful natural phenomenon called an earthquake.
The shock that occurs when plates move is transmitted through seismic waves, which are divided into four types: P-waves, S-waves, L-waves, and R-waves. P-waves are the first to arrive, and while they generally don’t cause much damage, systems that detect them can quickly alert you to an earthquake. S waves arrive next, and that’s when the real damage starts to happen. Particularly powerful earthquakes can cause liquefaction, where the ground turns into a liquid, which can weaken the foundations of buildings and make them more likely to collapse.
An earthquake doesn’t happen all at once, but in several stages. It can be divided into three phases: the foreshock, which usually precedes the mainshock; the mainshock, which is the most powerful impact; and the aftershocks, which follow the mainshock. The mainshock can be followed by hundreds of aftershocks, which can also cause additional damage.
Although many people believe that there may be precursors to an earthquake, there are no scientifically validated precursors. For example, animals suddenly migrating in large groups or unusual cloud formations are often cited as precursors to earthquakes, but these stories lack scientific support. To date, there is no reliable way to predict earthquakes, and even in earthquake-prone countries like Japan, the emergency earthquake warning system is only able to detect P-waves and issue warnings as quickly as possible.
So what should we do when an earthquake strikes? The most important thing is to protect yourself from falling objects. If you are inside a building, the first thing to do is to hide under a table and protect your head. You might think that it is more dangerous to stay inside a building, especially if most buildings are made of concrete, as is the case in Korea, because of the high probability of collapse. However, if you leave the building during an earthquake, you are at risk of falling objects landing on your head, so it’s safer to stay in a safe place until the shaking subsides. Outside of buildings, it’s important to move to the widest, most open space possible, and it’s best not to move quickly during an earthquake, but to protect your head and wait for the shaking to stop.
Earthquakes are one of the few natural disasters that are beyond human control, and the more powerful they are, the more destructive they can be. No matter how thoroughly a building is designed for earthquake resistance, it is difficult to avoid collapse in an earthquake of magnitude 8.5 or higher. While there is no way to be completely safe from these disasters, preparation and education are essential to mitigate the damage. Living in a seismically designed building and knowing what to do in the event of an earthquake are the most important ways to protect yourself from an earthquake.